Autofocus cameras equipped with a rangefinder employing multiple flashes are known. Such a rangefinder comprises a plurality of light-emitting means emitting light to the subject, a light-receiving means that receives the light reflected from the subject for position detection, and an arithmetic processing unit which receives the output signal from the light-receiving means and calculates the distance to the subject.
The above-described rangefinder emits light in the following manner. The light-emitting means are activated by a driver circuit to emit a plurality of flashes successively during periods of time of t.sub.11, t.sub.12, t.sub.13, respectively, as shown in FIG. 4. The light-emitting means can be LEDs emitting infrared radiation which is passed through a single projector lens before falling on the subject. The reflected light is focused onto a position-sensitive photodiode. The arithmetic processing unit computes the distance to the subject from the focused position. Then, the focal distance of the lens is automatically adjusted.
In the aforementioned conventional method of driving the multiple flash rangefinder, the sum of the periods during which the infrared LEDs emit light, i.e., t.sub.11 +t.sub.12 +t.sub.13, is long and so a long time is taken to measure the distance. In addition, the LEDs produce a large amount of heat and, therefore, the peak current available is limited. Hence, a limitation is imposed on the light emission power. Consequently, the accuracy with which long distances are measured cannot be improved satisfactorily.